We adopted a cat, Mario, about 8 months ago. He is also black, and small. They aged him to about 4 years old. He was about 8 pounds when we got him, and quite scrawny from being on the streets. We’ve managed to fatten him up a bit, so now he looks like a normal, but small, cat. To echo everyone else, it’s not an issue, he’s perfectly healthy.
He was fixed shortly before we got him. Since he reached full maturity with his jewels intact, he has a deep, guttural voice, which is funny coming from such a little dude. And he likes to talk. A lot.